Add basic caching
#cache_key delegates to #object by default
Have to opt in with #cache_key
Clean up interface inconistency
Update railtie
updated and clarified readme. changed PostController to PostsController as it would be generated by rails. Also changed ApplicationSerializer to ActiveModel::Serializer
Prep for 0.5.0
add ActiveSupport.on_load announcement
Add support for customizing fields
Fix the build
Fix build for real
Add URL to serializers (closes #61)

Thanks so much to @vanstee for the initial
implementation!
Remove left over references to scope instance variable
Revert "Fix build for real"

This reverts commit 43f32c868a6bbe2c1061c8c58e0fdd9da43a29e3.
Fix build the correct way, ensure new apps work, closes #63
Fix the build on 1.8.7 :trollface:
use :root option in render :json

ArraySerializer can now render arrays with no root
delete identical test
rename test methods so tests run

incidentally test_array_serializer_with_root fails
`rails generate` runs correctly under Rails 3.0.x

* Rails 3.0.x does not yield `app` to `generator` blocks in railties.
  Picks a hopefully reasonable default `Rails.application` in that case.
* Fixes #71